Man has utilized air currents, and in particular winds, as a source of energy for many years to, for example, propel sail boats and operate water pumping windmills. Although conventional windmills operate satisfactorily under suitable conditions, high winds may subject the propellers to excessive rotational forces; higher winds and wind gusts may blow over their supporting structure or cause other damage. In addition, conventional windmills cannot be readily taken down or disassembled for movement to another location for replacement, or if dangerously high winds are expected to occur. Conventionally structured windmills are also expensive to install and take considerable time to erect.
With wear, conventional windmills develop wobble problems, and at any time will not turn when no wind exists and only rising air currents known as thermals are the only source of air current or air movement.